Preheat oven to 425 degrees F.

Spread tomatoes and garlic (skin on) in 1 layer onto a large baking sheet. Drizzle with 3-4 tablespoons olive oil and season with salt and pepper. Roast in the preheated oven for 30-35 minutes or until tomatoes are lightly charred on the outside and tender on the inside. Remove from oven and cool for 5 minutes then remove the skin off the garlic.

While the tomatoes are roasting, heat 1 tablespoon olive oil in a large pot or dutch oven. Add the onions and cook down on medium heat until golden , about 4-5 minutes. Add salt, pepper, the roasted tomatoes and garlic, broth, and basil leaves.

At this point, transfer the mixture to a blender and blend for 1 minutes or until the soup is creamy. This can also be done using a hand-held blender. Return the soup to pot and simmer for 5 minutes. Serve hot with your favorite grilled cheese!